Azure Functions is Microsoft’s answer to AWS Lambda.
It has many of the same functions as Lambda and leverages many of the same kind of terminology but it is well integrated with Microsoft’s ecosystem. The diagram below gives an example of this integration;
Microsoft provides two billing plans, the Consumption plan and the App Servoces Plan. On the consumption plan users are billed based on per-second resource consumption and executions. Consumption plan pricing includes a monthly free grant of 1 million requests. On the App Services Plan, if you are already using App Service for your other applications, you can run your functions on the same plan at no additional cost.
The Google Cloud Functions pricing is based on number of triggers (Google calls them Invocations) and per 100 millisecond code execution. You also get 2 million free triggers per month (double that of Microsoft).